In general, a sabot is a lightweight carrier for a projectile, or kinetic penetrator. Use of a sabot permits the firing of a variety of projectiles of a smaller caliber within a larger caliber weapon. A sabot fills the bore of the gun tube while encasing the projectile to permit uniform and smooth firing of the weapon. The projectile is centrally located within the sabot that is generally radially symmetrical. After firing, the sabot and projectile clear the bore of the gun tube and the sabot is normally discarded some distance from the gun tube while the projectile continues toward the target.
Advanced saboted kinetic energy tank ammunition is constructed using composite material for the sabot and depleted uranium for the penetrator. Unfortunately, depleted uranium corrodes readily when in contact with moisture or humid environments and graphite based composite materials. Moisture is not only a problem for the depleted uranium but the composite material sabot parts as well.
Sabots constructed from composite material are machined using conventional methods. Machining typically exposes raw fiber ends and surface micro-cracking in the outer and inner geometry of the sabot. Moisture wicks along the fiber paths. Further, the resin matrix of the composite material absorbs moisture. Moisture thus wicked or absorbed causes the composite part to increase in size and lose some of its mechanical properties. The resultant corrosion and composite part degradation may cause handling hazards, failures in chambering rounds, and other performance failures.
Prior solutions for the corrosion problem described above have focused on placement of a sealing bead of silicone material between the three segments of molded composite parts which comprise the sabot. This was done to prevent moisture from propagating down the flanks of the segments, which provide an unobstructed path for moisture directly to the penetrator. Unfortunately, silicone beading has proven substantially ineffective for preventing corrosion of a depleted uranium penetrator.
One theory that is believed to explain the cause of corrosion of the depleted uranium is that composite materials and depleted uranium, when assembled in the presence of water, form a cell that accelerates the corrosion of the depleted uranium. In order to break up the cell, either the anode (depleted uranium), cathode (graphite) or electrolyte (water) must be removed from the reaction. In one embodiment, the present invention breaks up the cell by adding a nonconductive barrier coating on the sabot, thereby removing the conductive composite material from contributing to the cell.